Bridge-type mechanical lap joint of a 100 kA-class HTS: Conductor having stacks of GdBCO tapes

Satoshi Ito, Yutaro Seino, Nagato Yanagi, Yoshiro Terazaki, Akio Sagara, Hidetoshi Hashizume

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


In this paper, we reported design, fabrication and test of a prototype 100-kA-class high-temperature superconducting (HTS) conductor, especially for joint section, to be used for segmented HTS helical coils in the FFHR-d1 heliotron-type fusion reactor. The conductor has a geometry of three rows and fourteen layers of Gadolinium Barium Copper Oxide HTS (GdBCO) tapes embedded in copper and stainless steel jackets and has a joint section with bridge-type mechanical lap joint. We introduced improved method to fabricate the joint based on pilot experiments and we were able to apply a current of ~ 120 kA at 4.2 K, 0.45 T to the sample without quench at joint. The obtained joint resistance was ~ 2nΩ, which was lower than our previous data. Though joint resistance increased with a rise in current and magnetic field, predicted joint resistance in the environment of actual helical coil in the FFHR-d1 was small enough to properly run the cryoplant of the reactor.

Original languageEnglish
Article number3405086
JournalPlasma and Fusion Research
Issue numberSpecialIssue2
Publication statusPublished - 2014


  • FFHR-d1
  • Fusion reactor
  • Helical reactor
  • High-temperature superconductor (HTS)
  • Joint resistance
  • Mechanical joint
  • Remountable HTS magnet
  • Segmented HTS magnet


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